1. Field of the Invention
The present invention relates generally to a machine for the injection of eggs, typically referred to as “in ovo” injection, and the method performed in such egg injection. More specifically, the present invention is directed to a machine and method for the automated injection of various substances into eggs, especially live vaccines for the control of diseases in chickens and other avian flocks.
2. Prior Art
Advances in poultry embryology have made possible the addition of various materials to the embryo or the environment around the embryo within an avian egg for the purpose of encouraging beneficial effects in the subsequently hatched chicks. The substances which may be added include antimicrobials such as antibiotics, bactericides and sulfonamides; vitamins; enzymes; nutrients; organic salts; hormones; adjuvants; immune stimulators, probiotics and vaccines. This in ovo injection technique can, for example, lead to an increased percentage of hatch. The chicks from eggs that are injected prior hatch may retain a sufficient amount of the injected substance so there is no need to inject the hatched bird. The chicks may grow faster and larger and experience improvement in other physical characteristics. Additionally, certain types of vaccinations which could previously only be carried out upon either recently hatched or fully mature poultry can now be successfully delivered in the embryonated chick.
Thus, in ovo injection has become an effective means for disease prevention in avian flocks. In the poultry industry, a high incidence of infectious disease increases the cull rate and causes a high rate of mortality during the growing stage of young birds. One example of the infectious diseases is Marek's disease. It is a viral disease of chickens resulting in a type of cancer, and is one of the most serious threats to poultry health. This virus lies latent in T-cells, which are a type of white blood cells. T-cells are an integral part of the immune system response which is the bird's natural defense against disease. Within three weeks of infection, the fatal virus manifests as aggressive tumors in the spleen, liver, kidney, gonads, skin and muscle of the infected bird.
It has been found that by proper selection of both the site and time of inoculation, embryonic vaccination can be effective in the control of poultry diseases. It is essential that the egg be injected during the final quarter of the incubation period, and that the inoculate be injected within either of the regions defined by the amnion or the yolk sac. Under these conditions, the embryo will favorably respond immunologically to the vaccine with no significant impairment of its prenatal development.
A live cell-associated virus vaccine of tissue culture origin typically contains the Rispens strain, the SB1 strain of the chicken herpes-virus and the FC 126 HVT strain of the turkey herpes virus alone or in combination. The vaccine is presented in glass ampules containing concentrated vaccine, typically 1000 doses each, with a specified titer defined as Plaque Forming Units (“PFUs”) The vaccine product is stored in a frozen condition typically in liquid nitrogen freezer and shipped in liquid nitrogen. A special sterile diluent is supplied in a separate package, typically a sealed plastic bag with appropriate injection port and delivery tube opening. The vaccine is reconstituted by thawing the frozen vaccine in the glass ampule. The ampule is then broken open and the liquid vaccine product is withdrawn from the ampule using a needle and syringe. The diluent is stored at room temperature until use when the concentrated vaccine product withdrawn from the ampule by the needle and syringe is then injected into the diluent contained in the sealed plastic bag through the bag injection port. The reconstituted vaccine is then ready for delivery from the sealed bag through the delivery tube.
There are various factors that affect the level of PFUs delivered by a live cell vaccine, such as Marek's vaccine, to an inoculated specimen. Most of these factors occur during the vaccine reconstitution and in the delivery process. The factors which affect the level of PFUs delivered to the egg have to do with vaccine handling, temperature, turbulence in the syringe, air pressure, friction, pH, vaccine delivery tube length, diameter and configuration, needle length and diameter, needle shape and delay in vaccine consumption after thawing. Elimination or reduction of the adverse effects arising from these noted factors would greatly improve the inoculation process for Marek's vaccine, specifically, and for live vaccines, generally.
The automated in ovo injection technique involves delivering a vaccine in fluid form to the interior of an egg using an automated machine which delivers the vaccine to the egg through a needle. The needle can be used to both penetrate the egg shell and deliver the fluid substances, or the opening in the shell can be performed separately in advance of the fluid injection. The egg can be injected at any location within the egg, and even into the embryo itself. The suitability of a particular location depends on the purpose for which the egg is being injected and the fluid substance delivered. Some substances must be delivered to a particular location within the egg in order to be effective. The problem with locating the needle at the appropriate injection point is that eggs vary in size, thus varying the distance between the shell and the location at which delivery of the fluid substance is desired. A primary goal of automated in ovo injection is to be able to handle a high egg volume in a short period of time while consistently delivering a correct amount of vaccine fluid to the desired location within each of the eggs and without contaminating the eggs.
Typically, the eggs are incubated by the hatchery in an incubating tray placed in an incubator or setter machine. After injection, the injected eggs must be transferred to a hatching tray to be placed in the hatchers or hatching machine. Usually, the eggs from two or more incubating trays are transferred to each hatching tray. Conventional incubating trays include the Chick Master® 54 tray, the Jamesway® 42 tray, and the Jamesway® 84 tray (in each case, the number indicates the number of eggs carried by the tray). The eggs from three Chick Master® 54 trays, or a total of 162 eggs, would be transferred to a single hatching tray; the eggs from four Jamesway® 42 trays, or a total of 168 eggs, would be transferred to a single hatching tray; and the eggs from two Jamesway® 84 trays, or a total of 168 eggs, would be transferred to a single hatching tray. There are some incubating trays, such as the La Nationale® incubating tray, which are sufficiently large enough to include a total number of eggs, in this case 132 eggs, such that the eggs from a single incubating tray would be transferred to its corresponding hatching tray.
Automated machines and methods for simultaneously injecting a large number of eggs are known. In one well known commercial machine, the eggs in the incubating trays are brought under a bank of injectors which house both needles and punches. First, the punches open a hole in the egg shell. Then, the needle is inserted into the egg through the open hole, followed by injection of the fluid. The punch is necessary because the needle is long and thin and can not repeatedly punch egg shells without bending and/or clogging. This system is shown, for example, in U.S. Pat. No. 4,691,063 to Hebrank. In another machine, such as shown in U.S. Pat. No. 6,240,877 B1, the injectors house a single needle which both punches the hole in the egg shell with a closed needle end and then delivers the fluid through a hole in the side of the needle tip. There are drawbacks to both of these prior art needle systems.
There is another major drawback in the two known automated machines and methods in that they inject the eggs in the incubating trays in sequence, rather than all at one time. The injecting needles must then be sanitized after each injecting sequence. Hence, the sequential injection of the eggs slows down the overall operation of the machine. Equally important, the sanitizing solution remains on the undersurface of the injection assembly and/or needles as they move over to the next section of eggs to be injected. This allows the sanitizing solution to drip onto the next group of eggs to be injected, thus raising potential contamination hazards.
Automated machines for simultaneously injecting eggs must also address the fact that eggs are not identical in size. In addition, they must take into account the fact that the eggs may be slightly tilted with respect to the injectors when carried in the egg depressions of the incubating trays. Because the depressions are designed to accommodate the varying sizes of eggs, the eggs are free to wobble in the depression. The ability to accurately and precisely control the travel of a needle within the egg is diminished when the egg is tilted, even where the relative vertical travel between the egg and the needle is carefully controlled to account for differences in egg height.
Different methods have been used for dealing with the varying egg size and egg position in the egg flat. In the aforesaid in ovo inoculating machine disclosed in U.S. Pat. No. 4,681,063, the injectors include a flexible cup at their lower end which serves to engage the eggshell for positioning prior to punching the hole and injecting the fluid or vaccine. One of the problems with this inoculating machine is that the suction cups used to secure and transfer the eggs during and after inoculation are right over the injection holes. Changes in pressure inside the egg can cause contamination in the eggs and an open suction area in the mouth of the cup can cause contamination into the cups. Then the dark wet surface areas inside the cups become a good place for mold and bacteria to grow. Subsequent injections then infect the subsequently injected eggs.
In the in ovo injecting machine of the other patent, U.S. Pat. No. 6,240,877 B1, the injectors include an articulating nesting cup at the lower end, which has a frustoconical inner surface to engage the eggshell. Then, when the injector body is held in position by the machine, the nesting cup holds the egg in position for punching and injecting the egg. One problem with this injector design is the large number of operating and moving parts which wear, fail, and/or become subject to fatigue, over time and must be repaired or replaced, with consequent downtime of the machine.
Existing in ovo injection machines are also believed to be damaging to live virus vaccines, such as Marek's vaccine, due to the destruction of the live cells from the time that the concentrated vaccine is reconstituted with the diluent, transferred from the storage container to the injectors through the machine tubing and passageways and finally delivered to the eggs through the injecting needles. The residence time of the reconstituted vaccine in the machine before delivery to the egg and the heat, friction and turbulence that the vaccine encounters as it moves through the machine from the storage container and out through the injecting needle are all highly detrimental to the live cells in known vaccines, particularly Marek's vaccine, and substantially reduce the PFUs which are delivered to the eggs through the injecting needles. It is believed that the known in ovo injecting machines could reduce the level of PFUs delivered from the injecting needles as much as 75%, and more, from the prescribed titer specified by the vaccine manufacturer.
While it was known that length of delivery time, heat and turbulence could be detrimental to the live cell count of various vaccines, including Marek's vaccine, it was not appreciated that these factors were causing significant live cell destruction in the in ovo injecting machines commercially available. More specifically, it was not appreciated that residence time of the vaccine in the machine, or the length of time the vaccine is subjected to heat in the machine, or the friction imparted to the vaccine while traveling through the machine, or the significant turbulence caused to the vaccine during the delivery process, could all significantly reduce the live cell count, or the PFUs of the vaccine, including Marek's vaccine, in the automated delivery of the vaccine to the egg. Furthermore, it was not appreciated as important that an automated in ovo injecting machine should be designed to reduce the adverse effect of these factors, i.e. residence time, excess heat, friction and turbulence, on the live cell count of the vaccines.
Turning to other aspects of known automated in ovo injection machines, they typically include a transfer section in the machine, after egg injection, to transfer the injected eggs from the incubating trays to hatching trays. In one well known machine, flexible suction cups, as disclosed in the aforesaid U.S. Pat. No. 4,681,063, are used to lift the injected eggs from the incubating tray for transfer to the hatching tray. However, as pointed out previously, these flexible suction cups cause a likelihood that bacteria and mold will enter subsequent eggs, thus creating the possibility of cross-contamination, since the same suction cups are used repeatedly in creating a reduced pressure inside the eggs through the injection hole. Other type transfer stations, or separate machines, are also known. Such separate transfer machines are disclosed in U.S. Pat. Nos. 5,107,794 and 5,247,903. One drawback of these latter transfer machines is the possibility of egg breakage as the eggs are rotated 180.degree. from the incubating tray (or egg flat) into the hatching tray.
Furthermore, known commercial in ovo injection machines have the eggs going into the machine and coming out of the machine from the same side of the machine or employ only a single tray track. More specifically, the operator places the incubating tray containing the eggs to be injected into the front end of the machine. After transfer of the injected eggs into the hatching tray, the filled hatching tray is removed by the operator also from the front or side of the machine. In more modern facilities, it may be more desirable for the incubating trays with the eggs for injection to be inserted at the front end of the machine, and have the filled hatching tray removed from the opposite or rear end of the machine. Such a through machine would permit the filled incubating tray and empty hatching tray to be loaded in a side-by-side relation at the front end of the machine, the trays to move parallel in-line through the machine, and the empty incubating tray and filled hatching tray after transfer to move away from the rear end of the machine by automatic operation. Such a design would allow the injection machine to operate more quickly and with less labor.
In addition to the foregoing, the known commercial automated in ovo injecting machines have a large number of mechanically operating components which are subject to wear, fatigue and failure during the long operating hours of the machine, thus requiring constant repair and replacement. The machine designs are also such as to allow dir, airborne contaminants, broken egg particles, etc. to collect in cracks, crevices and corners, which are not readily susceptible to cleaning or power washing. This contaminant accumulation can cause sanitation problems during the process of injecting the eggs under high speeds and over long hours of use.
For the foregoing reasons, there is a need for an automated injecting apparatus and method for simultaneously injecting eggs which are less labor-intensive than known systems, which can lend themselves to automated conveyor systems and which can be kept clean and free of debris collecting corners and crevices. The apparatus should handle a high volume of eggs with a high level of precision with respect to both the location and quality of vaccine delivered. The apparatus and method should also reduce the residence time of the vaccine in the machine prior to injection into the egg, reduce the amount of heat to which the vaccine is subjected prior to injection, reduce the friction to which the vaccine is subjected in the machine, and reduce the turbulence created in the vaccine during its passage from the vaccine delivery bag through the machine apparatus, tubing and needle and into the egg.
Ideally, fluid delivery should be quick, gentle and precise so as not to damage live vaccine cells. The apparatus design and overall method of operation should be sanitary so as to minimize, if not eliminate, cross-contamination and allow for good machine cleanability. The machine design should also minimize operating mechanical parts and facilitate both manufacture and operation, thus reducing manufacturing, operating and maintenance costs as compared to known machines and methods.